Motorola APX 1000 Detailed Service Manual page 731

Theory of Operation
: Controller
3.2.2.1.2 External Regulators: V_SW_1.4, V_SW_3.60
The controller board contains two TPS62050 regulators in order to regulate voltages of 1.4V and
3.6V. The TPS62050 is a synchronous step-down adjustable regulator. The switching regulator is
capable of sourcing 800mA. Its output can be adjusted by using a voltage divider tied to the feedback
pin. The regulators are powered from SW_B+.
regulator. Figure 3-16.
SW_B+
R6547M6
0
C6569M6
10UF
R6552M6
illustrates the supporting circuitry for the TPS62050.
V_1.55
VCC_SW1.4_VIN
R6554M6
100K
0
R6558M6
165K
R6548M6
0
DNP
Figure 3-16. V_SW_1.4 Switched Power Supply
Figure 3-16. is the schematic for the V_SW_1.4
SW1V4_FB
U6507M6
C6582M6
6.8PF
TPS62050
8 4
EN
PG
5 9
FB
SW
6 2
LBI L6505M6
LBO
7 10UH
SYNC
V_SW_1.4
R6568M6
301K
C6570M6
330PF
C6584M6 C6586M6
10UF 4.7UF
3-27